1. Field of the Invention
The present invention relates to a distributed power and protection system, and more particularly, to a system and method for distributing and controlling power of various magnitudes for motorized transportation means such as yachts, trucks, buses, motor coaches, recreational vehicles, tractors, turf and garden equipment, material handlers, generators, compressors, and commercial and residential applications among others.
2. Description of the Related Art
Several designs for distributed and power protection systems have been designed in the past. These systems of protection require that the cognizant engineer have prior knowledge of the loads being driven-their operating ampacity, transient response, and voltage requirements. These system requirements enable the design engineer to select the appropriate over-current protection device for the load being driven. Depending on the type of load being driven, the over-current protection device chosen could be a fuse or a circuit breaker. However, any change in these load requirements would require a complete re-design of the power distribution system and its characteristics. Since some loads, such as motors, require a an in-rush or pulse tolerance at start-up, engineers have to de-rate or modify the trip delay of the circuit breakers, in order to accommodate the characteristics of the motor load. Secondly, to accommodate this higher current rating, they also have to use heavier gauge wire. All this makes for a very inefficient system. None of them, however, provides for the setting of intelligent circuit breakers that are programmed on the fly by sensing the power characteristics of the load. These characteristics of the load can also be displayed automatically. Additionally, the present invention detects reverse polarity. And, finally, the present invention also detects arcing conditions.
Owing to the drawback of conventional methods, it is the object of this invention to introduce an automatic load detection circuit. This circuit will sense the different loads requesting power and automatically configure and adapt to the output transient response, start-up-current, operating current window, and rise time.
Using this concept, engineers can now design in the proper gauge wiring (generally smaller, and lighter) to support the actual operating current requirements of the load.
Current methods of over current protection, which involve the use of electro-mechanical devices such as thermal or magnetic circuit breakers, are designed to detect “dead shorts” in a circuit path before breaking the connection. However, momentary dis-connections, which may be caused by loose electrical hardware, can cause the circuit to arc and melt the wire insulation while remaining un-detected by the thermal or magnetic circuit breakers thereby leading to a hazardous condition. Also owing to this drawback, it is another object of this invention to automatically detect this arcing state and take appropriate action, usually to shut down the offending circuit, and alert appropriate personnel to the condition of that particular output.
In electrical power distribution systems, as shown in FIG. 2 of the present application, it is necessary to supply well-regulated and appropriately protected power to a plurality of loads. Such loads may not only be physically located remotely from one another, but may also have voltage and current requirements, which differ markedly from one load to another. To accommodate such loads, it is common to use a single bulk power supply to feed a common bus, which in turn, feeds a plurality of local bus sub-systems. This power supply is designed to provide a very high ampere output, typically 30 to 100 AC Amps or 50 to 500 DC Amps, that is protected by an over current protection device. This main high-powered bus then feeds a plurality of lower ampere-rated secondary bus sub-systems. These sub-systems are further protected by down-stream-over-current protection devices of various current ratings suitable for their appropriate loads being driven. These are fed to a third tier branch of over-current protections devices.
These bus strips and other interconnecting devices are of sufficient thickness so as to reduce voltage drops due to parasitic impedances inherent in interconnecting devices, and to maintain good electrical conductivity for optimum transfer of power.
While the above power distribution design is capable of providing well-regulated output power, it tends to be bulky and adds a significant amount of un-wanted mass to the electrical power distribution system. A more topologically efficient system is described and claimed in the present application.
Another drawback to the existing system is that although the circuit breakers are rated for specific amperage, their actual trip point typically falls anywhere between its rated current-carrying capacity and up to 135% of its rated capacity. Hence, a full load (F.L.) 20 Amp-rated breaker may not break until about 27 Amps is drawn through the circuit. Also, existing methods of protection from fire hazards require the designer to have prior knowledge of the load to be driven (inductive or resistive) in order to incorporate instantaneous or time-delayed over-current protection devices in the system. For instance, supporting a maximum current draw of 27 Amps. requires heavy gauge wiring and interconnecting devices (i.e. connectors) to safely transfer power to the appropriate loads. All this extra hardware adds significantly to the cost and creates a very heavy power distribution panel in the system.
Moreover, connecting these heavy gauge wires and interconnecting devices also adds a significant strain on manufacturing processes, requiring significant additional installation time and manufacturing labor as well as various types of mounting hardware and other secondary operations. Field replacement of the over current protection devices also become cumbersome since several hardware pieces have to be removed in order to un-install them.
The present conventional method uses a centralized wiring architecture wherein all of the power is distributed to the respective loads from a centrally located panel. In some applications, the panel is located in an area that prevents its immediate access. Any fault condition at the panel would require personnel to physically get to the panel to either identify or determine the cause of failure.
Other drawbacks of conventional power distribution systems are that manufacturers have to run long wires from the source of power to the loads. The long wire runs can add a significant amount of impedance thus causing voltage drops typically in excess of 10%. In order to minimize this drop, manufacturers have typically resorted to using very heavy gage wire to lower the impedance thus minimizing voltage drops. This heavy gauge wire routed throughout adds a significant amount of weight and cost.
This also results in additional labor costs and time for installation of this complex wiring structure, which raises manufacturing costs.
Applicant believes that the closest reference to this subject matter claimed herein corresponds to an intelligent power management system as described in Karuppana U.S. Pat. Nos. 6,465,908 and 6,377,031. Karuppana's patents describe systems that seek to avoid a breakdown in DC power sources, which may have limited power capacity, by diagnosing impending failures and cutting power off to targeted devices. However, the Karuppana patents do not address the drawbacks of the current method, which requires long heavy gauge and complex wiring and significant manufacturing costs. Karuppana does not disclose the use of current sensing devices over an initial period of time from the application of a voltage to a load to determine the characteristics (resistive or inductive) of a load. Furthermore, Karuppana does not address the drawbacks of conventional power distribution systems with heavy gauge and complex wiring with significant high manufacturing costs. The present invention, on the other hand, provides for a distributed power system that also provides calibrated protection to the loads, as needed.
Other patents describing the closest subject matter provide for a number of more or less complicated features that fail to solve the problem in an efficient and economical way. None of these patents suggest the novel features of the present invention.